The use of picosecond laser methods provides an improvement of more than four orders of magnitude in our time resolution capabilities as compared with previous methods used to study dynamic processes. Kinetics on the picosecond time scale of the interactions of the heme-proteins, myoglobin, hemoglobin, and the isolated alpha and beta chains, with ligands such as carbon monoxide and oxygen will be investigated using picosecond laser methods. The primary goals are to determine the key physical and chemical processes involved in the relaxation of photo-excited free and ligand bound heme-proteins in order to obtain information on the effects of ligand binding on transient heme-protein conformations and pathways for energy degradation. It is a major objective to relate dynamic processes such as the photodissociation of the ligand bound heme-protein and subsequent recombination steps to the ligand, the heme-protein and the solvent environment. Picosecond laser techniques will be used to measure: (1) the time scale for photodissociation; (2) the kinetics of cage recombination which is dependent on the structure of the heme cavity and is key to understanding the origin of the photodissociation quantum yields; (3) the absorption spectra and time evolution of transient species such as the precursor to the "quickly reacting" form of hemoglobin; (4) the dynamics of energy transfer from the aromatic amino acid residues of the protein to the heme moiety; (5) excited state lifetimes and transient spectra of free heme-proteins in order to determine the role of ligands in energy relaxation. The effects of solvent variables, in particular pH (Bohr effect) and the organic phosphates ATP and 2,3-diphosphoglycerate (DPG), on kinetic properties will also be studied. The health-related implications of this work are in providing information on: interactions of heme-proteins with ligands; effects of ATP and DPG, known to be in red blood cells, may aid in understanding blood chemistry; energy degrading pathways may help in comprehending the effects of radiation exposure on heme-protein function.